Conventionally, a valve apparatus described in Patent Document 1 (JP 05-047649 U) is known as a tank-closing valve of a fuel vapor leak prevention device for a vehicle. The valve apparatus has a single valve, which is used as an electric valve and as a positive pressure relief valve. Valve bodies of both the electric valve and the positive pressure relief valve are made in common so as to configure the single valve.
In order to keep a pressure in a fuel tank within a predetermined allowable pressure range for protection of the fuel tank, a negative pressure relief valve is required to be provided in addition to the positive pressure relief valve. However, in Patent Document 1, it is difficult to integrate both the positive pressure relief valve and the negative pressure relief valve with the electric valve.
In Patent Document 2 (USP 2010/0269921 A1), a valve apparatus includes an integrated structure, in which an electric valve and a positive pressure relief valve are integrated, and a negative pressure relief valve. However, similarly to Patent Document 1, only one of the positive pressure relief valve and the negative pressure relief valve is integrated with the electric valve. Thus, in the valve apparatus, a flow passage of the negative pressure relief valve is separated from a flow passage of the integrated structure of the electric valve and the positive pressure relief, valve.
In Patent Document 2, although the electric valve, the positive pressure relief valve and the negative pressure relief valve are provided in the valve apparatus, a configuration of the flow passages in a valve housing may be complicated, and a pressure loss may be increased.